The present invention relates to pigments having the surface coated with a particular inorganic compound, and more specifically to white or colored pigments with improved capability for preventing change of the color caused when wet with water or oil and degradation in hiding performances thereof. Furthermore the present invention relates to cosmetics with the white or colored pigment blended therein.
White pigments such as titanium oxide or zinc oxide and inorganic colored pigments such as Indian red, yellow iron oxide, black iron oxide, and ultramarine blue pigment, or organic pigments such as tar coloring matter generally change the colors to darker ones when wet with water or oil with the hiding performances degraded. This phenomenon occurs because a light reflectance or a scattering effect of the surface of pigments becomes lower.
By mixing the white or colored pigment as described above in cosmetics used for making-up, there are provided effects such as those of covering defects of human skin such as wrinkles or masculae or a coloring effect to make human skin look more attractive. However, as time goes by after the cosmetic is applied to human skin and a surface of pigments blended therein is wet with skin fats or sweat, a reflectance or scattering capability of the pigments becomes smaller with a color tone of the cosmetic film changing and also with the masking capability becoming lower, so that the capability of the cosmetics to cover human skin degrades.
There has been used a method of giving water repellency or oil repellency to pigments by treating with silicon-based or fluorine-based compounds to improve a stability in use for a long time of cosmetics. With this kind of cosmetics, the cosmetic effect can be preserved for a longer period of time to some extent by making it harder to be wet with skin fat or sweat, but the adequate stability in use for a long time has not be realized.
Further there is a method of preventing or delaying a pigment from getting wet by simultaneously mixing porous silica or the like in cosmetics so that skin fats or sweat secreted in association with passage of time is absorbed in the silica or the like, but the effect is not adequate at present.
Further in some of the cosmetics with the white or colored pigments blended therein, sometimes oil and fat, moistener, a surfactant, an organic thickener, an organic solvent or the like blended in cosmetics may be oxidized or decomposed, which in turn degrades the appearance or performance. Also in cosmetics with certain types of colored pigments blended therein, active oxygen is generated, and this active oxygen may promote aging of human skin onto which the cosmetics is applied.
It is an object of the present invention to provide white or colored pigments, which do not suffer from color tone or hiding performances thereof even when the surface is moistened with water or oil, without spoiling coloring performance or hiding performance of the pigments themselves.
Further it is another object of the present invention to provide cosmetics which can preserve the excellent effect for a long period of time and does not change the color tone by oxidizing or decomposing organic compounds blended therein nor lower its appearance and performances.
In the pigments according to the present invention, surfaces of the pigments are covered with an inorganic compound having the refractive index of 1. 8 or below.
The inorganic compound is preferably silicon oxide. The pigments are preferably inorganic pigments comprising titanium oxide, zinc oxide, or iron oxides
In the cosmetics according to the present invention, the pigments are blended therein.